Apparatus for the continuous production of a random-filament fleece

ABSTRACT

AN APPARATUS FOR FORMING A RANDOM-FILAMENT FLEECE AND HAVING A SPINNING HEAD TO SUPPLY FILAMENTS TO A TRUMPETSHAPED AERODYNAMIC TAKE-OFF MEANS WHICH THROWS THE FILMENTS AGAINST A COLLECTING MEANS WHERE THE FILAMENTS ADHERE TO FORM A TUBULAR FLEECE.

3,621,531 nonucuon OF A -FILAMENT FLEECE N 23. 1971 KARL-HEINZ FELTGENETA!- MPAHATUS FOR THE CQNTINUOUS P RANDOM Filed July 28, 1969 2Sheets-Sheet 1 Q 1. 1'5 M 404 KL Mag g F Am/wgxr Nov. 23, 1971 R -H zFELTGEN ETAL 3,621,531

APPARATUS FOR THE CONTINUOUS PRODUCTION OF A RANDOM-FILAMENT FLEECEFlled July 28, 1969 2 Sheets-Sheet 2,

FIG. 2

FIG. 3

#m M 0N P, /5 0 #w W M A k m w W ..U M G 3,621,531 APPARATUS FOR THECONTINUOUS PRODUC- TIUN BF A RANDOM-FILAMENT FLEECE Karl-Heinz Feltgen,Dormagen, and Gunther Espanion,

Cologne, Mauenheim, Germany, assignors to Farbenfabriken BayerAktiengesellschaft, Leverkusen, German y Filed July 28, 1969, Ser. No.848,138 Claims priority, application Germany, Sept. 7, 1968, l? 17 85302.0 Int. Cl. DOld 23/00 US. Cl. 18-8 W13 2 Claims ABSTRACT OF THEDISCLOSURE An apparatus for forming a random-filament fleece and havinga spinning head to supply filaments to a trumpetshaped aerodynamictake-off means which throws the filaments against a collecting meanswhere the filaments adhere to form a tubular fleece.

There are numerous processes for producing randomfilament fleeces fromendless filaments arranged at random, for example from synthetic highpolymers. In all these processes, a bunch of endless filaments iscontinuously run off either directly from a meltor dryspinning machinefor the corresponding polymer or from an element used for theafter-treatment of filaments such as these, for instance rollers orcylinders, and is deposited in a random arrangement, but with as uniforma density as possible, for example onto a porous revolving conveyorbelt. The take-off forces required are applied mechanically, for exampleby means of a pair of rollers, or aerodynamically to the filaments, andtheir irregular random distribution can be obtained eitheraerodynamically by utilising turbulence or even electrostatically be therepulsion of similarly charged filaments, thus preventing them frombunching, or by a combination of both measures.

If they are to be economically further processed, random-filamentfleeces such as these, for instance textile sheet structures, must inpractice have a minimum width of approximately 1 metre. Someapplications require widths of up to 3 metres and more. One diflicultycommon to all manufacturing techniques lies in the difficulty ofachieving economic production of these widths coupled with uniformdensity over the entire width and the absence of seams. Seams areobtained when the fleece web is formed from several narrow bandssimultaneously deposited alongside one another, or when a relativelynarrow random-filament band is deposited in a zig-zag or meanderingarrangement from an element, for example a slot die, reciprocatingperpendicularly to the direction of movement of the fleece web in thecourse of formation, the length of stroke corresponding to the requiredwidth of the fleece.

On account of the necessity for consistency of speed over the length ofthe stroke, all reciprocating movements require mechanisms that are notonly complicated but also prone to wear. Depending on the kinematicsinvolved in traversing, more or less wide zones of high or low densityare always formed along the edges of the fleece web. These zones have tobe cut off and are discarded as waste. Compared, however, with all thepossible and Patented Nov. 23, 1971 obvious alternatives for making thewidth of the bundle of filaments to be deposited equal to the requiredwidth of the fleece from the outset, the traversing method has certainadvantages. As will readily be appreciated, a marked anisotropy of thephysical properties such as strength, elongation and shrinkage ispeculiar to a fleece prepared by the first method on account of thepreferential orientation of the filaments in the longitudinal direction,i.e. in the direction of travel of the fleece web produced. Both inaerodynamic and in electrostatic processes for the production ofrandom-filament fleeces, allowance must always be made for thepossibility of the deposition length not being uniformly covered byfilaments. Differences in density such as these would result inelongated streaks in the final fleece if no precautions were taken i.e.by traversing across the fleece as it is being formed, to ensure thatevery part of the depositing mechanism passes over every part of thefleece being formed.

In order, therefore, to avoid the aforementioned disadvantages, allconventional processes for the production of random-filament fleecestolerates the difficulties of traversing mechanisms referred to earlieron.

The object of the present invention is to provide a process and anapparatus not employing any of these traversing mechanisms. The processaccording to the invention not only makes it possible to obviate theaforementioned disadvantages without any need for complicatedmechanisms, it also embodies some important modifications which simplifythe apparatus as compared with conventional apparatus for the productionof random-filament fleeces.

The process according to the invention for the continuous production ofa random-filament fleece employs the method whereby a plurality offilaments is drawn off aerodynamically by means of a gas jet. Theinventive feature is that, by using at least one annular jet which,after engaging the bundle of filaments, is deflected axiallysymmetrically, the filaments are blown in one plane on to the wall of acollecting unit, randomly to all sides, but in a uniform density, andform a tube which is continuously drawn off.

In this way, a tubular random-filament fleece is formed which is uniformin density over its entire periphery, and the uniform density is alsoconstant over its entire length providing the manufacturing conditionsremain constant.

Preferably, the gas is removed through gas-permeable walls in thecollecting unit. This is of particular advantage in the production ofrandom-filament fleeces of fairly high density, because this measureprevents the tubular structure formed from fluttering.

In one particularly advantageous embodiment of the process, the bundleof filaments sucked in and the tubular fleece formed are pivoted orrotated with respect to one another. In this way, a further improvementrelating Irotropy of the fleece generated is being achieved.

In another particular embodiment of the process according to theinvention, the tubular fleece formed is moistened, for example withsteam or a liquid, thus increasing cohesion of the fleece duringdraw-off.

According to another embodiment of the process, the tubular fleeceformed is preferably cut up in order to obtain a single-layer fleeceweb. In another embodiment of the process, the tubular fleece is cutinto a plurality of webs in order to obtain suitable processing widths.

The main advantage of the process according to the invention does not,however, lie only in the homogeneous density of the fleece webs, butalso in the possibility of using all the material produced without anywaste because no irregular, useless marginal zones are formed.

In terms of known features, the apparatus for carrying out the processaccording to the invention comprises a filament or yarn dispenser,preferably in the form of a spinning head or a frame with supply rollersand takeoff cylinders, an aerodynamic take-off means and means forcollecting the random-filament fleece.

The inventive feature is that the aerodynamic take-off means comprise atube into whose wall opens at least one annular slot die arrangedconcentrically to the axis of the tube, the outlet end of the tube beingwidened like a trumpet and surrounded at a distance by the collectingmeans.

In one advantageous embodiment, the outlets for the filaments paid outby the dispenser are uniformly distributed over an annular surface, thusensuring uniform density of filaments along the inlet circumference ofthe aerodynamic take-off jet-advice.

In order to further enhance this uniformity, a distributor element isarranged above the inlet end of the take-off means. This distributorelement comprises, for example, a disc surrounded externally by thefilament, or a ring being touched by the running filaments either frominside or from outside. The distributor element may also be providedwith guide grooves for each individual filament. Preferably, it isarranged at a variable distance from the take-off means.

The distributor element is alternatively provided around its peripherywith an encircling blow nozzle connected to a source for pressurizedpreferably heated, gas. This ensures that the filaments are guided inthe total absence of friction. The object of heating the filaments witha heated gas issuing from the nozzle is to increase the temperature ofthe filaments traveling past to such an extent that, under the filamenttension produced by the resistance to drafting in the melting zone justbeneath the spinneret an additional molecular orientation going beyondthe quick draft is obtained by heat-stretching.

A displacement means is preferably arranged in the trumpet-like wideningof the tube of the take-off means. It is possible in this way moreeffectively to deflect the gas stream, aXi-symmetrically together withthe filaments, and to minimise energy losses.

In another particular embodiment of the apparatus, the collecting meanscomprises a perforated jacket arranged concentrically to the centralaxis of the take-off means. The carrier gas can penetrate through thisperforated jacket. Preferably, the perforated jacket is removablyattached so that perforated jackets of different diameter can beselectively used for the production of tubular random-filament fleecesof corresponding diameter. In one embodiment, the perforated jacket isin the form of a contractable sleeve. In this embodiment, however, thejoin in the perforated jacket adversely affects formation of the fleece,and additional precautions have to be taken to cover this join.

In another preferred embodiment, the collecting means is coupled with amoistening means, for example in the form of spray nozzles for steam orliquid.

At least one cutter unit is preferably arranged, on or behind thecollecting means, for cutting up the tubular fleece into one or moresingle-layer webs.

In another advantageous embodiment, the collecting means is heatable toenable the filaments to weld together.

Preferably, the take-off means is, with advantage, mounted in such a waythat it can be pivoted or rotated. Alternatively to or in combinationwith this, the collecting means is pivotally or rotatably mounted. Thepivoting range and speed or the rotational speed are preferablyvariable.

The random-filament fleece according to the invention is distinguishedby the fact that it is in the form of a seamless tube. In a particularembodiment, the randomfilament fleece comprises a web cut from aseamless tube.

The process according to the invention and the apparatus according tothe invention are diagrammatically illustrated by way of example in theaccompanying draw ings, wherein:

FIG. 1 is a longitudinal section through the apparatus.

FIG. 2, which is drawn on a larger scale, shows a particular embodimentof the distributor element in the form of a blow nozzle with a take-offmeans, and

FIG. 3 is a plan view of the collecting means with rotary drive.

As shown in FIG. 1, a bundle of up to several thousand individualfilaments 1 issues from a spinning head acting as filament dispenser 2,the holes of the spinneret 3 being uniformly distributed over an annularsurface 4. A distributor element 6 which is mounted concentrically tothe annular surface 4 and which uniformly distributes the filaments 1before they are drawn into an aerodynamic take-off means 7, is arrangedon a vertical shaft 5 attached to the spinning head at a suflicientdistance beneath the spinning head 2. The aerodynamic take-off meanscomprises an annular chamber 8 into which flows compressed air at 28 top.s.i. atms. The annular chamber 8 surrounds a tube 9 and forms parts ofthe wall of this tube 9, which at its lower end is widened like atrumpet at 10. An annular slot die 11 is arranged in the tube 9,extending over its entire periphery. On leaving the slot die 11, thecompressed air expands into a thin high-speed jet flowing along incontact with the wall of the tube 9, taking the filaments 1 with it. Thejet remains in contact with the Wall even in the trumpet-like widening10 of the tube 9 because provision is made for an adequate pressure allover the free sides of the jet so that the radial pressure gradientrequired for curving the fiow line can be supported. This effect isenhanced by a displacement means 12 inserted into the trumpet-likewidening 10 of the tube 9. In this way, the quantity of secondary airtaken in from above is limited by the resulting reduction incross-section, with the result that the partial vacuum in the tube 9 isreduced. On the other hand, the displacement means 12 ensures that anyair entrained flows off in an orderly axially symmetrical manner. Theflow pattern is thus similar, for example, to an axially symmetricalflow of the kind developed when a jet or stream impinges vertically on aplate. The bundle of filaments 1 follows this flow pattern and is thrownat random against a collecting means 13 comprising a perforated jacket.The takeoff means 7 is rotatably mounted in the bearings 14 and isperiodically pivoted back and forth by a drive 15 in conjunction with acam 16 and crank arms 17. In this way, an extremely uniform texture isimposed upon the tubular random-filament fleece 18 which is removed atthe lower end of the collecting means 13. The air penetrates through theholes in the perforated jacket 13 and in doing so presses the filaments1 and the tubular hose 18 in the process of formation against the wallof the perforated jacket 13. The tubular hose 18 is moistened with steamor liquid, or possibly with a special preparing liquid, by means of anozzle ring 19. Moistening promotes adhesion of the filaments although,with certain fibre polymers, it gives rise to some shrinkage so that thetubular fleece 18 readily detaches itself from the perforated jacket 13.The tubular fleece 18 is folded by means of two take-off rollers 20,behind which there is a cutter unit 21 which cuts up the tubular fleece18 so that two fleece webs 22 and 23 are formed, being wound up onto therollers 24 and 25.

The take-off means 7 is shown on an enlarged scale in FIG. 2. Thedistributor element 6 is provided around its periphery with a blownozzle 26, the shaft 5 being hollow for the delivery of gas or air. Thefilaments 1 are held apart by the jet of air 27 issuing from the blownozzle 26 so that there is no friction on the distributor 5 element 6.The filaments 1 and the propellent jet 28 take secondary air with them.

FIG. 3 shows purely diagrammatically how the collecting means 13 isrotated by the drive 30 in conjunction with belt 31, in order to impartto the tubular fleece 18 in the course of formation a spiral texturesuperimposed upon the meander texture imparted by the reciprocatingtake-off unit 7.

We claim:

1. An apparatus which comprises a spinning head in which the outlets forfilaments are distributed uniformly over an annular surface, anaerodynamic take-off means located beneath the spinning head, adistributor element arranged above the inlet of the take-off means,means for collecting random-filament fleece, said aerodynamic take-offmeans comprising a tube into whose wall opens at least one annular slotdie arranged concentrically to the axis of said tube and an axisymmetricdisplacement means being arranged concentrically to the axis of saidtube to periodically pivot the tube back and forth, the outlet end ofthe tube being widened so as to be trumpet- UNITED STATES PATENTS1,500,931 7/ 1924 Hooper 57-58.89 UX 3,149,944 9/1964 Leaman 65---14 X3,254 482 6/1966 Stalego 57-58.89 X 3,265,477 8/1966 McCoppin 188 RX3,325,906 6/1967 Franke l8-8 BX J. SPENCER OVERHOLSER, Primary ExaminerM. O. SUTTON, Assistant Examiner US. Cl. X.R.

201 SM; 5758.89; 65-5, 16; 264--176 R

